内蒙古林西地区上二叠统林西组烃源岩有机岩石学特征

内蒙古东部林西地区是二连盆地外围石炭-二叠系油气勘探的重要潜力区之一．为了研究上二叠统林西组烃源岩有机岩石学特征，对野外露头剖面的林西组烃源岩开展了总有机碳、有机显微组分、镜质体反射率及岩石热解等测试分析.结果表明：林西组烃源岩总有机碳分布在0.63%～1.30%，平均为0.87%，所有样品含量均大于0.6%；有机显微组分分布在0.27%～3.66%，平均值为2.08%，其中95.24%的样品达到1.0%以上，表明有机质丰度达到了“较好”至“好”级别；镜质体反射率分布在1.26%～2.58%，平均值为1.88%，其中90.47%的样品含量大于1.3%，镜质体反射率较高，表明有机质成熟度达到“高成熟”至“过成熟”阶段；岩石热解氢指数分布在8×10-3～89×10^-3，平均为27.52×10^-3，表明有机质类型归属于Ⅲ型.综合评价表明林西地区上二叠统林西组烃源岩属于“较好—好”烃源岩，生烃潜力较大，具有较好的油气资源前景.

ORGANIC PETROLOGY OF SOURCE ROCKS FROM THE UPPER PERMIAN LINXI FORMATION IN LINXI AREA,INNER MONGOLIA

Linxi area in eastern Inner Mongolia is one of the important potential areas for Carboniferous-Permian oil-gas exploration in the periphery of Erlian Basin. The total organic carbon (TOC), organic macerals, vitrinite reflectance and rock pyrolysis of the source rocks from Upper Permian Linxi Formation in field section are tested and analyzed to study the organic petrological characteristics of the source rocks. The results show that the TOC content of source rocks is 0.63%-1.30%, averagely 0.87%. The content of organic macerals ranges from 0.27% to 3.66%, averagely 2.08%, with 95.24% of the samples above 1.0%, indicating that the organic matter abundance is at relatively good-good level. The vitrinite reflectance(R_o) is 1.26%-2.58%, averagely 1.88%, with that of 90.47% of the samples more than 1.3%, showing the organic matter is in high mature-overmature stage. The hydrogen index of rock pyrolysis is 8×10^-3-89×10^-3, averagely 27.52×10^-3, reflecting that the organic matter belongs to III-type. It is concluded from the comprehensive evaluation that the source rocks of Upper Permian Linxi Formation are relatively good-good, with great hydrocarbon potential and good prospect of oil-gas resources.